Articles
BULBING AND FLOWERING OF IRIS BULBS STORED AT DIFFERENT TEMPERATURES BEFORE A COLD TREATMENT
Blaauw’, grade 7–8 cm, were subjected to a 6 week treatment at 9°C either immediately after lifting or after a 2 week storage at 15°C or 30°C. After cold treatment, the bulbs were placed at 15°C and bulbing was observed.
Bulbing started earlier and then continued faster when the 9°C treatment was applied to bulbs previously stored at high temperature, 30°C. This result suggests that a high-temperature treatment, applied immediately after lifting, has a favourable effect on the subsequent bulb reserve mobilization necessary to ensure daughter-bulb growth.
In a second experiment, bulbs of ‘Ideal’, grades 10–11 cm and 9–10 cm, were stored at 30°C immediately after lifting or were first stored at 20°C during 2 weeks and then at 30°C. 4 weeks after lifting for the 10–11 cm and 6 weeks after lifting for the 9–10 cm, the bulbs received a cold treatment, 6 weeks 9°C + 2 weeks 17°C, and were then planted at 14°–16°C in a growth chamber.
Storing the bulbs at 30°C immediately after lifting caused : earlier sprouting, shorter period to flowering, higher percentage of flowering.
Storing the bulbs at 20°C increased the leaf number per plant and the percentage of blasted flowers.
The favourable effect of high temperature on subsequent flowering is discussed.